The present invention relates to irrigation sprinklers, and more particularly, to an improved velocity control disc for an inlet valve assembly of a pop-up sprinkler.
The use of irrigation systems for watering plants where rainfall is inadequate is common throughout the world today. One of the most widely used systems, particularly for lawns and athletic fields, is a sprinkler system wherein a plurality of pop-up sprinklers are positioned about a land area for uniformly distributing water in accordance with a watering program executed by a controller. These sprinklers have a telescoping riser which retracts into a fixed sub-surface housing when not in use. When pressurized water is supplied to the sprinkler, the riser extends or pops-up from the sub-surface housing to eject a stream of water.
Sprinklers of this type are widely used on golf courses and other turf applications. These are usually high pressure systems and are frequently subjected to significant forces each time water is supplied to them, particularly when they are supplied with a high pressure combination of air and water. These high forces over a lifetime of use can damage sprinklers and reduce their useful life. The highest forces result when a sprinkler is subjected to surge conditions, such as when the system is being winterized or being refilled with water in the spring. In climates where irrigation systems are subject to freezing, the water must be removed from the system before winter. The water is purged from the system by means of compressed air. The compressed air acts much more rapidly than water and usually results in the risers shooting up rapidly with very high forces resulting in damage to the sprinklers. High surge forces also frequently occur when empty pipes are being filled with water. As the lines are being filled, air or a combination of water and air is forced into each sprinkler and vented through the same. Under these conditions the riser frequently shoots up at a high velocity and is slammed against the stationary outer housing with relatively great force.
Attempts to solve this problem by making the sprinklers heavier and stronger have been unsatisfactory because of increased costs. The dual medium of water and air makes unsatisfactory the use of slow opening valves to control the out-flow.
Another problem frequently encountered in so-called xe2x80x9cvalve-in-headxe2x80x9d sprinklers is that large particles get trapped between the moving valve member and seat during closing of the valve. This results in continuous leakage until the sprinkler is cycled again. The valve seat can also be damaged.
Therefore, there is a need for a means for reducing the extension velocity of the riser of a pop-up sprinkler in order to prolong its life. There is also a need for a valve-in-head sprinkler design that reduces the tendency for large particles to become trapped against the valve seat.
Accordingly, it would be desirable that a sprinkler be available having a means for reducing the riser extension velocity to prevent the resultant high forces and consequential damage. It would also be desirable that a sprinkler have some means for reducing the tendency for large particles to become trapped against the valve seat.
Accordingly, it is a primary object of the present invention to provide a pop-up sprinkler having an improved inlet valve assembly for controlling riser extension velocities and reducing high forces normally resulting therefrom.
In accordance with the present invention, a pop-up sprinkler includes an outer housing having an inlet passage and an inlet for connection to a source of pressurized fluid. A riser is in the housing for moving from a normally retracted position to an operative extended position in response to fluid pressure. A pressure responsive inlet valve assembly is mounted in the outer housing adjacent the inlet passage and includes a valve seat and a valve member. The inlet valve assembly further includes a velocity control disc that is biased into engagement with the valve seat. The velocity control disc initially meters inlet fluid for limiting a rate of opening of the valve member for controlling flow of fluid through the inlet and extension of the riser to the extended position. The velocity control disc is made of an elastomeric material and is deflectable radially inwardly to accommodate debris.